Global warming which causes climate change has a significant social economic impact. Indonesia's commitment to protecting the global climate has been a concern since the 1990s. Through Presidential Regulation No.61 of 2011 concerning the National Action Plan (RAN) for Reducing Greenhouse Gas Emission, each region needs to develop climate change mitigation actions through reducing emission or increasing the absorption of Greenhouse Gases (GHGs) from various emission sources. The formulation of climate change mitigation actions needs to be supported by greenhouse gases inventory activities and measurement of emission. Measurement of GHG emission is a cross-sectoral activity. Therefore, an information system through an electronic GHG calculator platform is needed as an instrument for measuring GHG emission that can support districts/cities to formulate the most relevant mitigation actions. This study describes the sources of GHG emission based on energy use and its measurement using GHG calculator. GHG calculator is developed based on the theoretical context and designed in form of mobile application. Using Focus Group Discussion (FGD) technique and Spearman's correlation analysis, this research aims to evaluate GHG assessment based on the use of mobile application in Surabaya City. The findings of this study are 1) there is positive feedbacks regarding the use of mobile platform to predict and calculate GHG emission. It shows that perception on easiness and usability level of mobile calculator are correlated significantly; 2) there are some opportunities and challenges in implementing mobile application for measuring GHG emission in Surabaya City
